Radio receiving circuit



w. KAUFMAN RADiO RECEIVING CIRCUIT Filed Anril 14, 1923' m u M 0m March15,3927.

March 15 1927.

w. KAUFMAN RADIO RECEIVING CIRCUIT Filed April 2 Sheets-Sheet 2 IN VENTOR ATTORNEY b Patented Mar. 15, 1927; I v v I UNITED STATES- ATENTQFFICE.

V I v tor rarnnsom ivnw annsny. a fpmmomoawmqcm mq I Application filedApril 14.19212. s ria norcsiess."

This invention relates to radio receiving the'usual grid condenser 6which is preferapparatus and more particularly to a novel ably shuntedby the resistanceelement' 7 circuit employed for the reception'of radioand-thence to the filam'ent8of the audion 5, communication, and :has forits object the through the coil9','which is inductively. and

provision of a circuit which is simple in variably coupled with the @112in the pristructure and schematic layout, eflicient in mary circuit. Theplate electrode 10 of operation and which in operation has dcaudion 5is'connected to'thegrid'electrode 4, cided advantages over othercircuits forsimpreferably at a "point between the grid conilar purposes.denser 6 and the secondary coil 9. This con- 10 A further object of theinvention isto nection is made preferably through a con provide acircuitwhich with but few'parts denser "1 2, and a high resistance path 13is'simple in operation and highly efficient in is provided between theplate and grid selectivity. a electrodes. A variable tap connection-14is Further objects of the invention Will 2113- provided fortheinduct'ance coil 11, which 15 pear more fully herein. I r tapconnectionhastwo'paths,oneto ground he invention consists'substantiallyin the 3 and the other through telephone receiversconstruction,combination, location and rela- 15, space currentsource 16,to filament 8 of tive-arrangementof parts, all as will be more audion 5.If desired, and as shown, the fully hereinafterjset forth, as shownbythe telephone receivers 15may'be shunted by a" c panying drawings andfinally pointed condenser 17 The primary and secondary out in theappended claims. A circuits; in accordance with my inventionareReferring to the drawings: f p ,1' .f "connected througha variablecapacity 18, as I Fig. 1 is aschematic view ofa circuit em shown. InFig. 2 -tl1e schematicarrangebodying my invention. ment isslightlymodified. I

. 25 Fig. 2 is a similar view ofa slightly .modi In this arrangement thetap coiinection 14 fied arrangement employing the circuitof is, asbefore, provided with twopaths, one my invention. I I j of-which leadstothe aerial land the other The same part is designatedby the same throughthe variable inductance 2 to the reference character wherever it occurs.ground 3 and the telephone receivers 15, 30 throughoutthe severalviewsfi f" either with or 'without the shunting con- It is among the specialpurposes of my denser thereabout, and connected'between"the presentinvention to provide an electrical primary circuit and the secondarycircuit, circuit and inethod of operation or a radio i. e., between thefilament electrode and receiving system and apparatus for obtainground.The'filament electrode 8 is lighted 35 ing maximum amplification of thereceived in theusu'al' well-known manner from'a cursignal impulses bymeans of certain modi rent" source 2t) through a variableresi'stficationand alteration'of the ordinaryauance'Q/l, g f diondetector and amplifier circuits, and While I am not prepared at thistime thereby obtain results" with a single tube to give a full and"complete scientific or 1 whichv wou'ldjbe impossible in accordanceanalytical explanation of the operation or 9.9

with the systems now known without addithis circuit, I do notdesiretobe'lim'ited to or tional tubes or stages of amplification.bound' by any theoretical consideration Referring to Fig.1, whichillustrates a thereof, hejoper'ation ofwhichcircuit-obsimple schematicwiring arrangement e1n- 'tains thefollowing results? bodyingmyinvention, reference character In the firstplace, the circuit isextremely 5 1 designates the antenna vwhichis connected eflicient' forthe receptionoftelephone sigthrough the variable inductance tubeto thenails, and when being operated to receive earth 3; The secondary circuitof the'retelephone signals reception of'spark signals ceiving systemincludes the grid electrode is for all practical purposes eliminated.and

50 A of the audion 5 which is connected through thereby eliminates thedisadvantageous-ef- 9 tion of continuous wave signals.

fects of damp wave signaling on the recep- By controlling the variableelements-namely, the tap connection 14 of the inductance 11 of the platecircuit-the tap connection on the primary inductance 2 and the condenser18 bridged between the primary and secondary circuits, I have-found thatit, is possible to obtain great selectivity and completely tune outadjacent stationsoperatin'g on a-=definite*- wave length and receive adistant station operating on the same wave length without interference.I have also found the system to be especially adapted" for use inreception of continuousiwave signals and-the. audion 5 placed in'a stateof oscillation generation at a controllable. frequency whereby if thebeat notes method ofreception isrbeingemployedv the 'pitch or frequency.of. the beat notemay be readily controlled.

It will "be observed-that in each instance the circuit consists of acombined detector circuit and amplifier circuit; e. g referring to Fig.1, the 'detectorcircuit comprises the grid electrode l, the grid leak13, condenser 12,'the lower portion of the inductance 11, tap connection14,- ground 3, tuning. condenser 18 and filament electrode 8, with theusual plate circuit 10, inductance 11, telephone receivers 15 andBcurrent source '16. The amplifier circuit. will be apparent as follows:v

The gridfilament circuit consists of grid electrode 4, resistance 13,inductance 9,, to the filament electrode 8. The plate circuit inthisinstance comprises the plateelectro'de 10, a portion of theinductance 11, telephone receivers 15, and the B battery source 16 tothe filament- 8.

It may be that the foregoing constitutes one explanation for theefiiciencyof the drcuit employed but, as above stated, I I. do notdesire to be limited or restricted thereto as I desire to have theforegoingydescription recorded in the illustrative sense rather than inthe limiting. sense. I

In the practical operation of the system embodying my. invention certainrules of adjustment shouldpreferably beobserved to obtain theamaximunresults. course, these rules would differ somewhat inrac'cordancewiththe type of-signal (i. e., telephone or continuous wave) which is tobe received and the degree of selectivity desired.

Where radio telephone reception is desired, it is necessary to keepthesystem from oscillating, whereas in cont1nuouswavesig= nal reception itis necessaryv to produce oscillation slightly above orbelow the frequency of the-receiver signals, [in order.- to obtain beats of anaudible frequency in accordance with the Heterodyne method "ofreception.

It may be generally stated, however, that the frequency of the secondarycircuit is 'bination with an audion, having a grid-filathe use tliereoffin connection with wireless telephone or telegraph transmission orrec'eption" as distinguished from radio frequency signaling. systems,for it will be readily apparentto' those skilled in the art thatfeatures hereof may be employed in con-' nection wired wireless orcarrier current signaling. systempr any other type of electrical.sign'aling system .at' present employed'in connection with vacuumtubes.

Many further modifications and changes in details will readily beapparent" to those skilled in the art without dep artingf'rom the spiritandscope of my invention as defined in the claims,.but having now setforth the objects and vnature'of my invention andhaving shown anddescribed '-s tructures embodying the principles thereof, what I claimas new and useful and of my own invention, and desire to secure byLetters Patent is:

1. In a radio 'signaling system, the combination with an audion, havinga grid filament circuit, of a circuit including an inductance coilconnecting. the plate electrode oflthe audion-with thegr'id electrodethereof,

and a'variable connection between said coil and the filament electrodeof the audionindependently of said grid electrode connec- I tion. a

, 2. Ina radio signaling. system, the com- 'bination'with an audion,having grid-filament circuit and a direct current plate-fila mentcircuit, of an inductance included in. the plate-filament circuit, saiddirect current plate filament circuit having a'tap connection from saidinductance to ground, and a telephone receiver and voltage source,connected between said tap connect-ion a'ndfthe filament electrode ofsaid audion. 8. In a radio signaling syste1n,the coniment circuit, of acircuit including an inductance coil connecting. tlie plate electrode ofthe audion with the grid'electrojde thereof,

a variable'connection between'said co'illand ground, and a telephonereceiver and current source bridged between said connection and the'filament'electrode of' said audion,

said bridged connection having no portion. thereof'incommon with thegrid plat'e'circuit.

4." In a radio signalingsystem, an antennaearth circuit having aninductance therein, and an audion anditscircuits'with the gridfilamentcircuit thereof conductively associated with said antenna-earth circuitand the filament electrode of said audion, said grid-filament circuit,and a tuning condenser connection including a telephone receiver.connected between said antenna earth circuit 5. In a radio signalingsystem, the comand said grid-filament circuit. 10 bination with anaudion having grid-fila- In testimony whereof I have hereunto set 5 mentand plate-filament and grid-plate cir-- my hand on this 10th day ofApril A. D., cuits, of an antenna earth system including 1923. aninductance inductively coupled with the WOLFF KAUFMAN;

